1. Field of the Invention
This invention relates to ion exchange resins and, in particular, to ion exchange resins having reduced extractable organic compounds and methods of producing such resins.
2. Description of the Related Art
Ion exchange is a process that exchanges one ion in solution for another ion that is bound to a substrate. Typically, the ion in solution has a higher affinity for the substrate than the bound one. The ion in solution adsorbs onto the substrate, displacing (xe2x80x9cexchangingxe2x80x9d) the bound ion into solution.
Ion exchange is often used in water treatment, where ions in aqueous solution typically displace hydrogen (H+) or hydroxide (OHxe2x88x92) ions bound to a substrate. This is sometimes known as xe2x80x9cwater demineralizationxe2x80x9d or xe2x80x9cwater deionization.xe2x80x9d The substrate, such as a resin, is conventionally made from a polymeric material or a zeolite. The ions are exchanged stoichiometrically, maintaining electroneutrality of the system. A resin that exchanges one positive ion (or a proportionate quantity based on valency), such as hydrogen, for another positive ion, such as copper, iron, or sodium, is a cation resin; a resin that exchanges one negative ion (or a proportionate quantity based on valency), such as hydroxide, for another negative ion, such as chloride, sulfate, or chromate, is an anion resin. In many cases, both types of resins are used to remove various salts, such as sodium chloride or calcium sulfate, from solution. The resin may be used until it becomes saturated with the ions being removed; however, many resins may also be regenerated and reused. For example, resins used in water treatment may be regenerated by using strong acids (cation resins) or strong bases (anion resins).
Ion exchange columns or beds containing resins are commonly used in industries where purity of water may be important. Ion exchange columns are especially important in industries with closed-loop circulation systems, such as those used in cooling equipment, where ion concentrations may increase to high levels because of the lack of an outlet for ions leaching from the surrounding piping and equipment. Ion exchange columns also see use in industries with high purity water requirements, such as in semiconductor manufacturing, or condensate polishing in the nuclear power industry.
The present invention provides an ion exchange resin material. The resin is treated so that it comprises less than 200 parts per trillion by wet weight of adsorbed total organic carbon extractables, as determined by a gas chromatography/mass spectrometry test.
In another embodiment, the present invention provides a method of treating an ion exchange resin material. A resin is provided and contacted with an organic solution to produce a resin with less than about 200 parts per trillion by wet weight of adsorbed total organic carbon extractables, as determined by a gas chromatography/mass spectrometry test.
In another embodiment, the present invention provides a method of maintaining an ion concentration in a solution. The solution comprises an ethanolamine buffer. The solution is passed over an ion exchange resin material for a total period of usage greater than about three months. During such time, the ion concentration in solution remains below about 100 parts per trillion, as determined by gas chromatography/mass spectrometry test.
In another embodiment, the present invention provides a method of treating an ion exchange resin material. An ion exchange resin material is provided and contacted with a solution comprising a first concentration of an amine. The resin material is then contacted with a solution comprising a second concentration of an amine.
In another embodiment, the present invention provides a method of treating an ion exchange resin material. A resin material is provided and contacted with water at a temperature greater than about 130xc2x0 F. The material is also contacted with a solution comprising ethanolamine. The material is also contacted with a solution comprising a mineral acid.
In another embodiment, the present invention provides a mixed ion exchange resin. The mixed ion exchange resin comprises a first ion exchange resin material comprising less than about 200 parts per trillion by wet weight of adsorbed total organic carbon extractables as determined by a gas chromatography/mass spectrometry test, and a second ion exchange resin material.
Other advantages, novel features, and objects of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings, which are schematic and which are not intended to be drawn to scale. In the figures, each identical, or substantially similar component that is illustrated in various figures is represented by a single numeral or notation. For purposes of clarity, not every component is labeled in every figure, nor is every component of each embodiment of the invention shown where illustration is not necessary to allow those of ordinary skill in the art to understand the invention.